Running your own gfServer

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BLAT servers (gfServer) are configured as either dedicated or dynamic servers. Dedicated BLAT serves index a genome when started and remain running in memory to quickly respond to request. Dynamic BLAT servers pre-index genomes to files and are run on demand to handle a BLAT request and then exit.

Dedicated gfServer are easier to configure and faster to respond. However, the server continually uses memory. A dynamic gfServer is more appropriate with multiple assemblies and infrequent use. Their response time is usually acceptable; however, it varies with the speed of the disk containing the index. With repeated access, the operating system will cache the indexes in memory, improving response time.

Both database-based assemblies or assembly hubs may be configured to use either type of BLAT server.

Configuring a dedicated gfServer

  • If you want to run your own BLAT server you need a lot of spare memory on the machine. You may also want to review our mailing list archives for gfServer troubleshooting advice.
  • Run two instances of gfServer from at the location of yourAssembly.2bit file, specifying a port that the gfServer will be accessible from for amino acid (-trans option) and DNA searches. Please note the -mask option will ignore all lower-case assembly sequence, which is the convention the UCSC Browser uses for masked sequence, so you may not want to include it from the example below.
 * When picking a port number, stick with numbers between 1024 and 49151. Anything less than 1024 is considered a system port and you'll need to be root in order to open it. Anything above 49151 is considered dynamic and randomly assigned. 
  • For example, these two lines will specify port 17777 for DNA searches
 and 17779 for amino acid searches and are run from the publicly accessibly
 directory location of yourAssembly.2bit file:
  cd /genomes/yourAssembly
  gfServer start blatMachine 17777 -stepSize=5 -log=yourAssembly.untrans.log yourAssembly.2bit &
  gfServer start blatMachine 17779 -trans -mask -log=yourAssembly.untrans.log yourAssembly.2bit &

Adding something like this to a startup file of your server, e.g. /etc/rc.d/rc.local, will ensure they are started when your system is rebooted.

Configuring database genomes to use a dedicated gfServer

  • Tell the browser where to find the 2bit file with the SQL commands:
  update hgcentraldbDb set nibPath = "/genomes/yourAssembly" where name="yourAssembly";
  • On RedHat you might need SELinux permissions:
  sudo chcon --type=httpd_sys_content_t /gbdb/yourAssembly/yourAssembly.2bit
  • Add the server to the hgcentral database with the SQL commands:
  update hgcentral.blatServers set host = "localhost", port=17777 where db="yourAssembly" and isTrans=0;
  update hgcentral.blatServers set host = "localhost", port=17779 where db="yourAssembly" and isTrans=1;
  • If you're not running a protein server, remove its entry from hgcentral with the SQL command:
  delete from hgcentral.blatServers where db="yourAssembly" and isTrans=1;

Configuring a dynamic gfServer

A xinetd super-server starts a dynamic BLAT server to handle a single user request. It loads a pre-built index from disk for the request A single xinetd server handles multiple genomes and, nucleotide, protein-translated, and protein queries. Genomes indexes must be pre-built, with all of them installed or linked under a common directory hierarchy, called the gfServer root directory.

Configuring xinetd

The xinetd, or the older inetd server is a standard package on UNIX /Linux systems. It is a facility that runs a program to handle an internet server request. A system administrator generally configures it. The server runs the services as an unprivileged users. Please see your operating system documentation for more details.

An example configuration file below. It launches gfServer with two arguments, the literal string "dynserver" and the gfServer root directory path.

service blat
         port            = 5010
         socket_type     = stream
         wait            = no
         user            = blatuser
         group           = genecats
         server          = /mnt/data/dyn-blat/bin/gfServer
         server_args     = dynserver /mnt/data/dyn-blat/genomes
         type            = UNLISTED
         log_on_success  += USERID EXIT
         log_on_failure  += USERID
         disable         = no

Building gfServer indexes

Three files are required by dynamic gfServers and must follow the naming convention:

  • yourAssembly.2bit - two-bit format genomic sequence
  • yourAssembly.untrans.gfidx - untranslated index
  • yourAssembly.trans.gfidx - translated index

Where yourAssembly is the database or hub name of the assembly. For database-based assemblies, the files are stored in a directory with the name as the assembly database, such as rootdir/yourAssembly/. For assembly hubs, they may follow this convention or use more deeply nested directories such as rootdir/GCF/000/181/335/GCF_000181335.3/.

The gfServer parameters are stored with the index and are specified when the index is created. The following commands will build the indexes:

  gfServer index -stepSize=5 yourAssembly.untrans.gfidx yourAssembly.2bit
  gfServer index -trans yourAssembly.trans.gfidx yourAssembly.2bit

Configuring database genomes to use a dynamic gfServer

Existing mirrors will need to add a column "dynamic" to hgcentral.blatServers with the following SQL command:.

  alter table hgcentral.blatServers add column dynamic tinyint not null default 0;

To change an existing genome to use tghe dynamic gfServer, use the SQL commands:

  update hgcentral.blatServers SET host = "localhost", port=5010, dynamic=1 where db="yourAssembly" and isTrans=0;
  update hgcentral.blatServers SET host = "localhost", port=5010, dynamic=1 where db="yourAssembly" and isTrans=1;

RAM requirements for BLAT servers

The gfServers that provide responses for blat queries can take some amount of memory. Here is some information that might help in approximating the required amount for genomes of different sizes.

The human hg19 genome requires ~2.2GB for the translated amino acid gfServer queries
and ~2.2GB for the untranslated DNA gfServer queries representing ~3,137,161,000 bp.
The zebrafish danRer7 genome requires ~1.2GB for the translated amino acid gfServer queries
and ~1.1GB for the untranslated DNA gfServer queries representing ~1,412,465,000 bp.
The D. melanogaster dm6 genome requires ~300MB for the translated amino acid gfServer queries
and ~250MB for the untranslated DNA gfServer queries representing ~143,726,000 bp.